Compression inner tube for tires



July 3; 1923.

G. 'R. COLBY COMPRESSION INNER TUBE FOR TIRES v Filed Sept. 1 2Sheets-Sheet 1 Fj. III

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AZZor/1ey.r

July 3, 1923.

G. R. COLBY COMPRESSION INNER TUBE FOR TIRES' -Filed Sept. 17, 1921 2Sheets-Sheet 3 9 IFIVQHZOF: 1. f (o y my 7 AZfor-neys Patented July 3,1923.

UNITE GEORGE re. COLBY, or PORTLAND, onneon.

COMPRESSION INNER TUBE FOR TIRES.

Application filed September 17, 1921. Serial .N'o. 501,303.

ing pneumatic tires, and has for its object the production of an inner,inflatable tube which, when filled with'a'ir at required pressure, willeffectually resist deflation through puncture.

My tube belongs to that class in which the walls of the tube are made ofelastic material, such as india-rubber, that is 'thickor heavy incross-section as contra-distinguished from the thin, bladder-like tubesnow in general use.

Heavy walls of that description possess two distinct advantages. One'advantage they have over thin tubes is that when once inflated theyhold, by reason of their thickness, air without leakage, and requireinflation only at long intervals of time, whereas, thintubes, howeverapparently airtight, are porous, and are, therefore, subject to constantleakage,'which, although imperceptible at any instant of time,necessitate pumping up at short intervals in order to maintain effectualair pressure within the tube. This affords in itself one distinct gainin the use of heavy tubes generally over thin ones, wherein my inventionparticipates.

The second advantage referred to is that a heavy tube possesses, byreason of its elasticity, a transversely distributable potentialforce,which it has been conceived to be possible to transmit through thebody of the material composing the tube with the result of efi'ectuallyclosing said body against leakage of airby puncture. The necessity fortransmitting said force throughout the entire body of the tube does notappear to have been heretofore conceived.

The. principle of excluding leakage in pneumatic tires in the mannerjust referred to, that is, by compression laterally of the body of athick,,elastic inner tube, is already recognized in the art astheoretically practicable and desirable. The earliest proposal known toapplicant for carrying that principle into efi'ect is by providing inthe tube a circumferential channel formed by a fold or depression in thebody of the tube, which, I

upon inflation of the tube, is designed to fill the hollow ofan'encasing tire, with compressing effect uponthe material composing thebody of the tube. Itis found in practice, however, that such a channelor fold cannot be relied upon to effect, with certainty andcompleteness, the object intended. The reason is that it is impossible,by such means,

to attain inpractice the end proposed in theory. If the channel is madetoo shallow, i

the tube, in rounding out to its full capacity, must either stretch ormust simply, that is, without any or without suflicient compression,fill the space provided for its accommodation. in either case, effectualcompression throu hout the body of the tube will be lacking. 6n theother hand, if the channel is too deep, or, in other words, the foldcon- 'stituting the channel is too voluminous, the

effect of attempt at inflation of-the tube to its capacity will be'toproduce .a buckling in the body of the tube, thereby causing astretching of the material at certain points which defeats the purposeintended. Wherefore, even if a tube having a single channel be regardedas theoretically possible for the purpose under consideration, it isdependent for success upon such and so many minute factors, as to becommercially uneconomical if not entirely impracticable.

The present invention has for its object the elimination of the abovementioned defectsv in construction heretofore employed, and seeks toprovide a tube which, when de fiated, has a plurality of indentationsadapted to be forced outwardly when the tube is inflated and thereby tocompress the entire tube mass. Another object of the invention is toarrange the indentations in such away that upon inflation of. the tubeand theset-v ting up of the compressing stresses there is a completebalancing of the stresses, whereby the compression is uniformlydistributed throughout the tube mass, and there is no tendency for thetube to move within the shoe. A. further object of the invention has odo with the arrangement of, the indentations in such a way that the tubeis. suitably locked in position within the shoe when the tube isinflated and is properly centered automatically upon inflation. I f

The above and other objects ofthe invention-0f a more minutecharacter,'which are more intimately associated with the details"accomplished by providing a tube having a plurality of series ofindentations, preferably dish-shaped, the series being disposedcircumferentially of the tube and in substantial parallelism. The seriesof indentations are divided by passive areas which are substantiallycontinuous and entend circumferentially of the tube. T ese passive areasare arranged in parallelism and contact with. the inner surface of ashoe while the tube is deflated. The individual indentations of theseries are divided by transversely extending passive areas which contactwith the in ner surface of the shoe while the tube is de flated. Thesepassive areas in each series are staggered with respect to the passiveareas in the adjacent series, and the indentations of each series arestaggered with respect to the indentations of the adjacent series.

What constitutes my invention will be hereinafter described in detailand succinctly set forth in the appended claims.

In the accompanying drawings,

Figure I is a side elevation, partly in iongitudinal section. of asector of a tire, showing my invention in present preferred form ofembodiment.

' Figure 11 is a transverse section on the line 11-11 of Figure I.

Figure HT is a transverse section on the line III-III of Figure 1.

' Figure IV is a diagrammatical develop ment of the inner tube, as shownin Figure 1.

Referring to the numerals on the drawings, 1 indicates a pneumatic tire,which may be of any ordinary or suitable type designed and adapted toform a case for an inner, inflatable tube 2, from whose inflation in useit takes shape. The casing 1 is made of suitable wear-resistingmaterial, and its construction may be varied according to preference.The inner tube 2 is made of elastic material like india-rubber, that isadapted, under inflation, to fit snugly against the surrounding wall ofthe encasing tire.

In commercial use, the tires and tubes are proportionate in size with asize of tube provided for each size of tire.

According to my invention, the outside diameter of each cross-section oftube is made substantially equal to the inside diameter of its tire,which allows for the slight inequalities that occur in manufacture.Consequently, if the inner tube were circular in shape. its outside wallwould touch the inside wall of the tire, substantially at all points, asindicated partially by dotted lines 3 in Figures II, and III. The saidcontact is in fact always preserved in respect to portions of the tube2, but in respect to the remaining portions of the tube, there iscontact only during inflation. When the tube is deflated, and when it isintroduced into the interior of the tire 1, the dish-shaped patchesconstituting compression elements 5 are not in contact with the insidewall of the tire, but are, by their own resiliency, set inwardly intothe hollow of the tube 2. hen the tube is inflated, under requiredinternal air pressure, the elastic material composing the elements 5 iscompressed by being crowded into restricted openings provided for theirrespective accommodation in the walls of the tube. Whereupon, each ofsaid elements exerts a laterally expansive force that communicatesitself, with compressing effect, upon the whole mass of elastic materialconstituting the tube.

In order to render the entire mass effectually permeable to theinfluence of said force, areas of demarkation are provided'in the wallsof the tube between the compression elements 5, along linescircumferential to tlie tube, of which there are preferably four,designated, respectively, by the numerals 6, '7, 8, and 9. there arecross areas extending between such of the lines 6 to 9 as are nextadjacent to each other. Along the lines 6, 7, 8, 9 and 10, respectively,there is constant contact with the tire 1 while the latter encases thetube The term line: in the above connection is intended to designategeneral disposition of contacting areas, and is not to be construed tobe limited to lines of mathematical exactitude. Understood according ly,the lines 6 to 10 indicate the location, also, of what may beaptlytermed passive areas, because they are areas that receive force from theelements 5, which are the active agents of compression. In a sense, thesaid areas. after they are charged with force by the 'l'nnctioning ofthe elements 5, become active agents for healing punctures; but that isdue only to retroaction, and during inflation of the tube 2.

Because of the passive nature of the areas aforesaid. it is necessarythat their respective transverse dimensions should be reduced to such ami imum as the compression derived fem the active elements 5 mayeffectuaily penetrate, it being taken into consideration that each ofsaid areas is acted upon directly by not less than tWo active elements.Consequently, as storage reservoirs of force, each of said areasreceives contribution of force from not less than two active orcompression elements. In fact, all of the compression elements coactindirectly, and, in some measure, to store up force through out theentire elastic mass composing the, tire; and it is only with a view toclearness, through simplicity of statement, that the direct action ofthe compression elements is emphasized.

It should be noted in this connection, that the disposition of the linesof passive areas is detern'iinate with respect to the tube encasingtire. and that the operative action of the elements 5 takes placebetween them With- Also, along lines 10' out materially disturbing theirrelationship to the tire. This constitutes one feature of my inventionthat is important, and distinctlve, inasmuch as it affords effectivemeans for storage of energy throughout the mass of the tube. By it, inconsiderable measure, is effected a balancing of force against force,without which, or without some such provision, a force of compressiongenerated in one part of a tube might be absorbed, and, in effect, lostin passive areas of excessive extent.

It is also noted that, upon inflation of my tube 2, no stretchingthereof anywhere occurs. Inflation serves only to compress the elements5 to the point of'contact with the inner face of the tire 1, whichresists any stretching tendency. It is compression only that does thework.

What I claim is:

1. An inner tube for pneumatic tires'having, in deflated condition, acontour to fit the inside of a shoe and provided throughout its entirearea with a plurality of circumferentially extending series ofindentations, which indentations upon inflation of the tube Within atire, are forced outwardly by the filling air to compress the remainder,

of the tube mass, said series being separated by passive areas adaptednormallyto contact with the inside of the tire shoe, the passive areasbeing substantially continuous in straight lines circumferentially ofthe tube.

2. An inner tube as specified in claim 1, the individual members of eachseries being divided by passive areas extending trans versely of thetube, there being a plurality of such passive areas 1n each series andsaid passive areas in the adjacent series being staggered with respectto each other.

3. An inner tube for pneumatic tires having, in deflated condition, acontour to fit the inside of a shoe, and provided throughout its entirearea with an, assemblage of indentations, which indentations, uponinfia= tion of the tube within a tire, are forced outwardly by thefilling fluid to exert a compressing effect upon the entire mass ofmaterial composing the tube, saidindentations being arranged in aplurality of'sub'stantially parallelseries extending circu1nferentially, of the tube and divided bysubstantially parallel continuouspassive areas ex tending in straight lines ,circumferentially of thetube, said passive areas normally contacting with the inner surface of ashoe before the tube is filled with air and the individual indentationsof each series being staggered with respect to the indentationsl in theadjacent series.

4. An inner tube for pneumatic'tires having, in deflated condition,acontour to fit the inside of a shoe, and provided throughout its entirearea with an assemblage of indentations, which indentations, uponinflation ofthe tube within a shoe,'are forced outwardly by the fillingfluid to exert-a com-- pressing effect upon the entire mass of ma-.

terial composing the tube, said indentations being arranged in aplurality of. substan-v tially parallel series extendingcircumferentially of the tube and divided by substantially parallelcontinuous passive areasex tending in straight lines circumferentiallyof the tube. said passive areas normally contacting with the innersurface of a shoe before the tube is filled with air, the individualindentations of each series being staggered withrespect to theindentations in the adjacent series, and transversely. extending passiveareasbetween the individual inden tations of each series and normallycontacting with the inside of the shoe before the tube is filled. y

In testimony whe'reof,-I have hereunto set my hand in the presence oftwo subscribing witnesses. I

. p I GEORGE R. COLBY.

Witnesses:

W. .T. RIDEHALGH, Josnrn L. Ariana;

